1. Field of the Invention
The invention is concerned with a process for the construction of a rigid and tight joint between components using joining elements, a join made by this process and the application of a sleeve as joining element.
2. Description of the Prior Art
Numerous methods for the joining of components are known from physics and technology. Where metallic bodies are concerned, in many cases they can be joined together to form more or less monolithic workpieces in a simple manner by soldering, welding or using thermal shrinkage. If however, non-metallic objects such as ceramics, plastic or cermet bodies are to be joined to metallic components, difficulties are usually encountered. Brazing using suitable alloys is known in particular as being one of the tricky techniques for joining ceramic and metal components (e.g. G. M. Slaughter, "Ceramics and Graphite," chapter 24, p. 237-242 in Brazing Manual, American Welding Society, New York 1963; D. A. Canonio, N. C. Cole and G. M. Slaughter, "Direct brazing of ceramics, graphite and refractory metals," Welding Journal, August 1977). The braze used must sufficiently wet the surfaces of the objects to be jointed in order to guarantee an intimate and tight join.
The quoted conventional methods for making metal-ceramic joints require relatively high temperatures for all of the materials used in the total construction. Since the thermal expansion coefficients of metals and ceramics are very different, considerable stresses can occur, particularly with complicated shapes, which can lead to cracks during fabrication or in service. Often recourse has to be made to expensive constructions such as assembling the joint in layers in order to keep the stresses within tolerable limits. The brazes normally used require temperatures of 1000.degree. C. and over and the processes have to be carried out in a complicated apparatus under vacuum or a protective atmosphere. In the case of joins using shrink fits, the metallic components have to be heated to a temperature of several hundred degrees centigrade, in order to achieve the necessary strain for the join, in consideration of the small thermal expansion coefficients. This method is limited, however, on the one hand by the hot strength of the metal and on the other hand by the thermal fatigue strength of the ceramic, leading either to joins of inadequate strength and tightness or to cracks in the ceramics part. There is thus a definite need in the technical world for a solid, tight and easily made joint.